DNA studies, ancient

Keyser-Tracqui, C. and B. Ludes (2005), Methods for the study of ancient DNA, Meth. Mol. Bio. 297 (Forensic DNA Typing Protocols), 253-264. 

PCR) and compared with sequences in other individuals and modern specimens. However, ancient DNA is severely damaged and fragmented. Contamination of aged samples and extracts with modern DNA is a serious problem and, whilst the study of DNA in archaeological samples will constitute a major area of future activity in the discipline, current research will continue to focus on the authentication of samples of ancient DNA advances have been so rapid that perusal of the appropriate scientific journals is essential. For somewhat more recent views of the state of ancient DNA research, see Willerslev and Cooper (2005). 

Some imaginative writers have described scenarios in which researchers not only study the past, they recreate it. In Michael Crichton s 1990 novel Jurassic Park, scientists estabUsh a dinosaur park that resembles the Jurassic era by recreating dinosaurs based on ancient DNA sources. 

The PCR is an example of a biotechnology that touches other scientific disciplines (and even the movie industry). Consider the study of ancient DNA for tracking evolution. Several researchers have referred to this as molecular archeology, since preselected DNA, which has survived in ancient tissue for 45,000 years or more, can be sufficiently amplified to provide quantities that permit direct sequencing of the DNA. This approach, in effect, provides a time machine that enables students of molecular evolution to retrieve and study ancient DNA molecules and thus to catch evolution red-handed" (Paabo et al.). 

DNA extracted from archaeological specimens, ancient DNA (aDNA), provides the researcher a window into prehistory, allowing one to say something absolute about the genetic characteristics of someone or something that lived in the past. While modem DNA studies can make predictions about the past based... 

As illustrated by the examples above, the analysis of DNA extracted from archaeological specimens can provide unique insights about the past. However, the study of aDNA is methodologically challenging, primarily due to the problematical state of its preservation. As such, protocols developed specifically for the extraction and analysis of ancient DNA have been developed, of which we have highlighted one that we have developed over the past few years. Our protocol offers solutions to two of the most common problems associated with the study of aDNA the possible presence of contamination on the surfaces of samples and/or the co-extraction of PCR inhibitors. We are optimistic that with attention to proper aDNA protocols, data acquisition, and authentication of results, DNA extracted from archaeological specimens will continue to provide a wealth of information about the past. 

The polymerase chain reaction (PCR) is an ideal tool for the study of ancient DNA because it has the ability to amplify a small number of intact DNA molecules that exist in a complex mixture of large amounts of partially degraded and modified templates. Of crucial importance for the use of ancient DNA extracts is the extent to which the damage limits or inhibits the enzymatic reaction. An observation often made is that the maximum sizes of amplifiable products are reduced in old, damaged DNA compared to modem DNA extracts.14 This is also true for DNA from ancient bones, which seem in many cases to allow for longer amplifications than soft tissues. For example, we have determined the maximum size of amplifiable DNA from 3500-year-old moas found at a dry cave site in New Zealand and found that, whereas soft tissues allowed the amplification of pieces only up to 120 bp, bone extracts from the same individual yielded products of up to 380 bp. However, DNA extracted from a modem ratite bird easily allowed the amplification of pieces of over 1000 bp.15... 

The ultimate reason for amplifying ancient DNA is to learn more about the history of species or populations. This is mostly done by the use of comparative analysis of DNA sequences. Such studies do, in themselves, provide indications as to the authenticity of the sequences obtained. For example, when ancient or old populations are studied, extensive knowledge of the present-day descendant populations is necessary not only to make inferences about the history of the populations, but also to allow the investigator to evaluate the authenticity of the sequences by comparing the... 

Note that earlier studies describing the sequencing of much more ancient DNA such as that found in insects trapped in amher appear to have been flawed contaminating modem DNA was responsible for the sequences determined. 

There are two major areas of current research involving archaeological remains residue analysis and ancient DNA (aDNA). Organic chemists study the residues biochemists and geneticists study aDNA. Both of these areas of investigation are... 

Some of the more spectacular uses of PCR include cloning of ancient DNA from extinct species such as the woolly mammoth ruling out suspects in criminal cases by forensic science, and providing genomic markers (STSs) in chromosome-mapping studies used in the Human Genome Project (see Chapter 21). 

The polymerase chain reaction is credited with making possible the development of a whole new field of saidy, the study of ancient DNA. Labeled by some molecular paleontology, these studies recently... 

Bar-Gal, G.K., Ducos, P, Horwitz, L.K. (2003) The application of ancient DNA analysis to identify Neolithic cap-rinae a case study from the site of Hatoula, Israel. International Journal of Osteoarchaeology, 13,120-131. 

Jones, Martin. Archaeology and the Genetic Revolution. In A Companion to Archaeology, edited by John Bintliff, Timothy Earle, and Christopher S. Peebles. Malden, Mass. Blackwell, 2004. Reviews the expanding field of archaeogenetics by discussing the history of how DNA entered the held, the study of ancient DNA, human evolutionary studies, existing practices, and future prospects. 

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